Develop Reference

Azure - Python Dash Application

I have a Dash application and I have got some questions for the Azure (App Services) deployment. I use git in Deployment Center.
1) In my requirements.txt I have a packages that is causing the issue - pywin32. It gives me the below error during the deployment:
ERROR: Could not find a version that satisfies the requirement pywin32==302 (from versions: none)
ERROR: No matching distribution found for pywin32==302
It happens during the installation of dependencies.
2) When I remove pywin32==302 from requirements.txt, I can build and deploy however the applications shows me the error (I did before Flask deployment and it worked).
Any ideas how to fix it please?
Logs here:
2021-12-14T14:09:25.051923007Z Updated PYTHONPATH to ':/tmp/8d9bee966ce1769/antenv/lib/python3.8/site-packages'
2021-12-14T14:09:25.497472285Z [2021-12-14 14:09:25 +0000] [37] [INFO] Starting gunicorn 20.1.0
2021-12-14T14:09:25.500486120Z [2021-12-14 14:09:25 +0000] [37] [INFO] Listening at: http://0.0.0.0:8000 (37)
2021-12-14T14:09:25.504178862Z [2021-12-14 14:09:25 +0000] [37] [INFO] Using worker: sync
2021-12-14T14:09:25.507938905Z [2021-12-14 14:09:25 +0000] [39] [INFO] Booting worker with pid: 39
2021-12-14T14:09:26.617892557Z Application object must be callable.
2021-12-14T14:09:26.619256872Z [2021-12-14 14:09:26 +0000] [39] [INFO] Worker exiting (pid: 39)
2021-12-14T14:09:26.677663238Z [2021-12-14 14:09:26 +0000] [37] [INFO] Shutting down: Master
2021-12-14T14:09:26.677730439Z [2021-12-14 14:09:26 +0000] [37] [INFO] Reason: App failed to load.
/home/LogFiles/2021_12_14_pl0sdlwk00000V_docker.log (https://*****.scm.azurewebsites.net/api/vfs/LogFiles/2021_12_14_pl0sdlwk00000V_docker.log)
2021-12-14T14:04:22.384Z INFO - Stopping site ***** because it failed during startup.
2021-12-14T14:09:08.430Z INFO - Starting container for site
2021-12-14T14:09:08.430Z INFO - docker run -d -p 1972:8000 --name taxdevelopment_0_bbeb99e2 -e WEBSITE_SITE_NAME=***** -e WEBSITE_AUTH_ENABLED=False -e WEBSITE_ROLE_INSTANCE_ID=0 -e WEBSITE_HOSTNAME=*****.azurewebsites.net -e WEBSITE_INSTANCE_ID=31a267ed7b71ec86982412cc9dc4ad2f31ca2b8f51b692363aa765c405b03b84 appsvc/python:3.8_20210810.1
2021-12-14T14:09:08.431Z INFO - Logging is not enabled for this container.Please use https://aka.ms/linux-diagnostics to enable logging to see container logs here.
2021-12-14T14:09:10.641Z INFO - Initiating warmup request to container *****_0_bbeb99e2 for site *****
2021-12-14T14:09:33.292Z ERROR - Container *****_0_bbeb99e2 for site ***** has exited, failing site start
2021-12-14T14:09:33.294Z ERROR - Container *****_0_bbeb99e2 didn't respond to HTTP pings on port: 8000, failing site start. See container logs for debugging.
2021-12-14T14:09:33.300Z INFO - Stopping site ***** because it failed during startup.
/home/LogFiles/webssh/.log (https://*****.scm.azurewebsites.net/api/vfs/LogFiles/webssh/.log)

ERROR - Container *****_0_bbeb99e2 for site ***** has exited, failing site start
ERROR - Container *****_0_bbeb99e2 didn't respond to HTTP pings on port: 8000, failing site start. See container logs for debugging.
The error message shows that failing to start site on linux container. It might be using some additional references of your Dash application. You can use Container logs to view the detailed information of error.
Docker logs appear on the Container Settings page in the portal.
You can find the Docker log in the /LogFiles directory. You can access this via the Kudu (Advanced Tools) Bash console or by using
an FTP client to access it.
You can use our API to download the current logs.
Refer here
Any way you already removed the pywin32 == 302 from requirements.txt and you can check the same pypiwin32==302 in requirements.txt and remove it.
Refer here for more information

"[CRITICAL] WORKER TIMEOUT" in logs when running "Hello Cloud Run with Python" from GCP Setup Docs

Following the tutorial here I have the following 2 files:
app.py
from flask import Flask, request
app = Flask(__name__)
#app.route('/', methods=['GET'])
def hello():
"""Return a friendly HTTP greeting."""
who = request.args.get('who', 'World')
return f'Hello {who}!\n'
if __name__ == '__main__':
# Used when running locally only. When deploying to Cloud Run,
# a webserver process such as Gunicorn will serve the app.
app.run(host='localhost', port=8080, debug=True)
Dockerfile
# Use an official lightweight Python image.
# https://hub.docker.com/_/python
FROM python:3.7-slim
# Install production dependencies.
RUN pip install Flask gunicorn
# Copy local code to the container image.
WORKDIR /app
COPY . .
# Service must listen to $PORT environment variable.
# This default value facilitates local development.
ENV PORT 8080
# Run the web service on container startup. Here we use the gunicorn
# webserver, with one worker process and 8 threads.
# For environments with multiple CPU cores, increase the number of workers
# to be equal to the cores available.
CMD exec gunicorn --bind 0.0.0.0:$PORT --workers 1 --threads 8 app:app
I then build and run them using Cloud Build and Cloud Run:
PROJECT_ID=$(gcloud config get-value project)
DOCKER_IMG="gcr.io/$PROJECT_ID/helloworld-python"
gcloud builds submit --tag $DOCKER_IMG
gcloud run deploy --image $DOCKER_IMG --platform managed
The code appears to run fine, and I am able to access the app on the given URL. However the logs seem to indicate a critical error, and the workers keep restarting. Here is the log file from Cloud Run after starting up the app and making a few requests in my web browser:
2020-03-05T03:37:39.392Z Cloud Run CreateService helloworld-python ...
2020-03-05T03:38:03.285477Z[2020-03-05 03:38:03 +0000] [1] [INFO] Starting gunicorn 20.0.4
2020-03-05T03:38:03.287294Z[2020-03-05 03:38:03 +0000] [1] [INFO] Listening at: http://0.0.0.0:8080 (1)
2020-03-05T03:38:03.287362Z[2020-03-05 03:38:03 +0000] [1] [INFO] Using worker: threads
2020-03-05T03:38:03.318392Z[2020-03-05 03:38:03 +0000] [4] [INFO] Booting worker with pid: 4
2020-03-05T03:38:15.057898Z[2020-03-05 03:38:15 +0000] [1] [INFO] Starting gunicorn 20.0.4
2020-03-05T03:38:15.059571Z[2020-03-05 03:38:15 +0000] [1] [INFO] Listening at: http://0.0.0.0:8080 (1)
2020-03-05T03:38:15.059609Z[2020-03-05 03:38:15 +0000] [1] [INFO] Using worker: threads
2020-03-05T03:38:15.099443Z[2020-03-05 03:38:15 +0000] [4] [INFO] Booting worker with pid: 4
2020-03-05T03:38:16.320286ZGET200 297 B 2.9 s Safari 13 https://helloworld-python-xhd7w5igiq-ue.a.run.app/
2020-03-05T03:38:16.489044ZGET404 508 B 6 ms Safari 13 https://helloworld-python-xhd7w5igiq-ue.a.run.app/favicon.ico
2020-03-05T03:38:21.575528ZGET200 288 B 6 ms Safari 13 https://helloworld-python-xhd7w5igiq-ue.a.run.app/
2020-03-05T03:38:27.000761ZGET200 285 B 5 ms Safari 13 https://helloworld-python-xhd7w5igiq-ue.a.run.app/?who=me
2020-03-05T03:38:27.347258ZGET404 508 B 13 ms Safari 13 https://helloworld-python-xhd7w5igiq-ue.a.run.app/favicon.ico
2020-03-05T03:38:34.802266Z[2020-03-05 03:38:34 +0000] [1] [CRITICAL] WORKER TIMEOUT (pid:4)
2020-03-05T03:38:35.302340Z[2020-03-05 03:38:35 +0000] [4] [INFO] Worker exiting (pid: 4)
2020-03-05T03:38:48.803505Z[2020-03-05 03:38:48 +0000] [5] [INFO] Booting worker with pid: 5
2020-03-05T03:39:10.202062Z[2020-03-05 03:39:09 +0000] [1] [CRITICAL] WORKER TIMEOUT (pid:5)
2020-03-05T03:39:10.702339Z[2020-03-05 03:39:10 +0000] [5] [INFO] Worker exiting (pid: 5)
2020-03-05T03:39:18.801194Z[2020-03-05 03:39:18 +0000] [6] [INFO] Booting worker with pid: 6
Note the worker timeouts and reboots at the end of the logs. The fact that its a CRITICAL error makes me think it shouldn't be happing. Is this expected behavior? Is this a side effect of the Cloud Run machinery starting and stopping my service as requests come and go?

Cloud Run has scaled down one of your instances, and the gunicorn arbiter is considering it stalled.
You should add --timeout 0 to your gunicorn invocation to disable the worker timeout entirely, it's unnecessary for Cloud Run.

i was facing the error [11229] [CRITICAL] WORKER TIMEOUT (pid:11232) on heroku
i changed my Procfile to this
web: gunicorn --workers=3 app:app --timeout 200 --log-file -
and it fixed my problem by incresing the --timeout

Here's a working example of a Flask app on Cloud run. My guess is that your last line or the Decker file and the last part of your python file are the ones causing this behavior.
main.py
# main.py
#gcloud beta run services replace service.yaml
from flask import Flask
app = Flask(__name__)
#app.route("/")
def hello_world():
msg = "Hello World"
return msg
Dockerfile (the apt-get part is not needed)
# Use the official Python image.
# https://hub.docker.com/_/python
FROM python:3.7
# Install manually all the missing libraries
RUN apt-get update
RUN apt-get install -y gconf-service libasound2 libatk1.0-0 libcairo2 libcups2 libfontconfig1 libgdk-pixbuf2.0-0 libgtk-3-0 libnspr4 libpango-1.0-0 libxss1 fonts-liberation libappindicator1 libnss3 lsb-release xdg-utils
# Install Python dependencies.
COPY requirements.txt requirements.txt
RUN pip install -r requirements.txt
ENV APP_HOME /app
WORKDIR $APP_HOME
COPY . .
CMD exec gunicorn --bind :$PORT --workers 1 --threads 8 main:app
then build using:
gcloud builds submit --tag gcr.io/[PROJECT]/[MY_SERVICE]
and deploy:
gcloud beta run deploy [MY_SERVICE] --image gcr.io/[PROJECT]/[MY_SERVICE] --region europe-west1 --platform managed
UPDATE
I've checked again the logs you've provided.
Getting this kind of warning/error is normal at the beginning after a new deployment as your old instances are not handling any requests but instead they are idle at that time until they are completely shut down.
Gunicorn also has a default timeout of 30s which matches with the time between the time of "Booting worker" and the time you see the error.

for those who are entering here and have this problem but with django (probably it will work the same) with gunicorn, supervisor and nginx, check your configuration in the gunicorn_start file or where you have the gunicorn parameters, in my case I have it like this, in the last line add the timeout
NAME="myapp" # Name of the application
DJANGODIR=/webapps/myapp # Django project directory
SOCKFILE=/webapps/myapp/run/gunicorn.sock # we will communicte using this unix socket
USER=root # the user to run as
GROUP=root # the group to run as
NUM_WORKERS=3 # how many worker processes should Gunicorn spawn
DJANGO_SETTINGS_MODULE=myapp.settings # which settings file should Django use
DJANGO_WSGI_MODULE=myapp.wsgi # WSGI module name
echo "Starting $NAME as `whoami`"
# Activate the virtual environment
cd $DJANGODIR
source ../bin/activate
export DJANGO_SETTINGS_MODULE=$DJANGO_SETTINGS_MODULE
export PYTHONPATH=$DJANGODIR:$PYTHONPATH
# Create the run directory if it doesn't exist
RUNDIR=$(dirname $SOCKFILE)
test -d $RUNDIR || mkdir -p $RUNDIR
# Start your Django Unicorn
# Programs meant to be run under supervisor should not daemonize themselves (do not use --daemon)
exec ../bin/gunicorn ${DJANGO_WSGI_MODULE}:application \
--name $NAME \
--workers $NUM_WORKERS \
--user=$USER --group=$GROUP \
--bind=unix:$SOCKFILE \
--log-level=debug \
--log-file=- \
--timeout 120 #This

how to make my python-flask website available 24*7 using nginx and gunicorn

How to configure gunicorn to make sure my python-flask website is available 24*7 ?
The issue I am facing is: As soon I kill my terminal window, the website is no more reachable.
I am using rhel7.6 to host a website using python-flask.
I have configured nginx as the web server and gunicorn as the application server.
.
I will really appreciate if some one can help me in using/configuring gunicorn to make sure my website is available 24*7.
Please have some of my code as below:
[root#syed-dashboard-4 ~]# pwd
/root
[root#syed-dashboard-4 ~]#
[root#syed-dashboard-4 ~]# cat hello.py
#!/usr/bin/python
from flask import Flask
app = Flask(__name__)
#app.route("/")
def hello():
return "Hello magentabox!"
#if __name__ == "__main__":
# app.run(host='10.145.29.23',port=5000)
[root#syed-dashboard-4 ~]#
[root#syed-dashboard-4 ~]# gunicorn hello:app
[2019-07-17 10:34:11 +0000] [9346] [INFO] Starting gunicorn 19.9.0
[2019-07-17 10:34:11 +0000] [9346] [INFO] Listening at: http://127.0.0.1:8000 (9346)
[2019-07-17 10:34:11 +0000] [9346] [INFO] Using worker: sync
[2019-07-17 10:34:11 +0000] [9351] [INFO] Booting worker with pid: 9351
I am pretty new to web development and as I mentioned as soon I close the terminal, the website is no more reachable. I can share the nginx configuration logs as well if that helps fixing my issue.
Thanks much.

You can use the supervisor. This is the professional way to run your server for 24*7.
Please add below file in your supervisor config to run.
[program:your_project_name]
command=/home/virtualenvpath/your_env/bin/gunicorn --log-level debug run_apiengine:main_app --bind 0.0.0.0:5006 --workers 5 --worker-class gevent
stdout_logfile=/home/your_path_to_log/supervisor_stdout.log
stderr_logfile=/home/your_path_to_log/supervisor_stderr.log
user=your_user
autostart=true
autorestart=true
environment=PYTHONPATH="$PYTHONPATH:/home/path_to_your_project";OAUTHLIB_INSECURE_TRANSPORT='1';
Configure this in supervisor it will run for 24*7. And whenever your machine restarts it will auto start.

On Linux, you can start your app in a tmux session that you detach once you started your server.
# Create a new tmux session
tmux new -s server
# Start your gunicorn server
cd /path/to/app
gunicorn hello:app
# Detach the current tmux session using Ctrl - B + D
You can close your terminal and your server will still be running.

Google App Engine deployment issue- main app not found

I am trying to deploy my app using Google App Engine. I have edited app.yaml to reflect the flexible environment and also gave all the app information. Below is the app.yaml file.
runtime: python
env: flex
entrypoint: gunicorn -b :$PORT main:app
runtime_config:
python_version: 3
Once the deployment is in progress, I am getting the following error
[2018-08-24 06:57:14 +0000] [1] [INFO] Starting gunicorn 19.7.1
[2018-08-24 06:57:14 +0000] [1] [INFO] Listening at: http://0.0.0.0:8080 (1)
[2018-08-24 06:57:14 +0000] [1] [INFO] Using worker: sync
[2018-08-24 06:57:14 +0000] [7] [INFO] Booting worker with pid: 7
App Deployed
Failed to find application: 'main'
[2018-08-24 06:57:14 +0000] [7] [INFO] Worker exiting (pid: 7)
[2018-08-24 06:57:14 +0000] [1] [INFO] Shutting down: Master
[2018-08-24 06:57:14 +0000] [1] [INFO] Reason: App failed to load.
Please note that App Deployed is the line in my print statement. It is getting executed. But the deployment is getting failed
Thank you in advance

In your app.yaml, you're starting gunicorn with gunicorn -b :$PORT main:app. This tells it to look for the object app in the file main.py
The error you're getting comes from gunicorn and occurs when you have a main.py file, but it does not have an app object in it.
You probably want to set up a Flask app as follows:
from flask import Flask
app = Flask(__name__)
See a full example app here: https://cloud.google.com/appengine/docs/flexible/python/quickstart#hello_world_code_review

I have had the same issue.
Failed to find application: 'main'
The reason in my case was that I had a directory called also main in the root project directory.
drwxr-xr-x 2 user staff 64 Nov 30 10:12 main
-rw-r--r-- 1 user staff 1178 Nov 29 20:58 main.py
I guess gunicorn got confused.
The solution (worked for me): to rename main directory.
P.S. Just don't rename it to code directory. It will cause another issue with debugging in PyCharm. :)

My folder structure is looks llike this the main.py is not in the root directory how I can specify this in app.yaml file.
/app
|__main.py
app.yaml

Django + Gunincorn - deploy and stay connected to the port?

Correct me if I am wrong: I can use gunicorn to deploy a django project, for instance I can deploy my app - helloapp in this way:
$ cd env
$ . bin/activate
(env) $ cd ..
(env) $ pip install -r requirements.txt
(env) root#localhost:/var/www/html/helloapp# gunicorn helloapp.wsgi:application
[2017-05-18 22:22:38 +0000] [1779] [INFO] Starting gunicorn 19.7.1
[2017-05-18 22:22:38 +0000] [1779] [INFO] Listening at: http://127.0.0.1:8000 (1779)
[2017-05-18 22:22:38 +0000] [1779] [INFO] Using worker: sync
[2017-05-18 22:22:38 +0000] [1783] [INFO] Booting worker with pid: 1783
So now my django site is running at http://127.0.0.1:8000.
But it will not be available anymore as soon as I close/ exit my terminal. So how can I have it stayed connected to the port 8000 even if I have closed my terminal?

As with any long-running process, you need to run it as a service under some kind of manager. Since you're on Ubuntu, you probably want to use systemd; full instructions are in the gunicorn deployment docs. Note, you will also need to configure nginx as a reverse proxy in front of gunicorn.